A law change which cracked down on "cowboy" clampers took effect this month, and prevents parking companies from charging motorists more than $100.
Consumer NZ and the Automobile Association said today that operators who tried to charge more than the maximum amount were committing an offence punishable by a $15,000 maximum fine.
"Before the law change, wheel clampers could charge any fee they liked," AA principal adviser regulations Mark Stockdale said.
"Fees of $200 were common and in some cases were much higher than that. The new law makes it an offence for wheel clampers to charge more than $100."
The two organisations said that if any motorist was charged a fee of more than $100 they should remind the operator of the new law.
If they were still asked to pay more than the maximum, they should contact police on the non-emergency 105 number, they said.
The wheel-clamping law change came after several businesses indiscriminately clamped motorists and charged hundreds of dollars.
Motorists complained that they had only stopped for a few minutes or were unaware parking was not permitted because of unclear or ambiguous signage.
One of the most notorious examples was a West Auckland retail complex where a company called Elite Parking Services clamped shoppers' cars and demanded as much as $450 to get their car released.
In many cases, the shoppers had only been parked for a few minutes in what appeared to be a 120-minute parking zone.
Another business, Bamford Antiques in Ponsonby, gained a reputation for aggressively clamping motorists, in one case charging a couple $760 to get their car released.
The AA and Consumer NZ said that if the new law change failed to deter rogue clampers, a ban on clamping should be introduced.
An outright ban was considered but rejected by government officials during development of last year's law change, because they did not see it as a widespread problem.
The crackdown on wheel clampers was based on anecdote rather than hard evidence of a significant problems, officials at the Ministry of Business, Innovation and Employment said.